Linear polyethylene compositions with improved barrier properties

Abstract

A linear polyethylene (PE) polymer product with improved barrier properties and mechanical properties, and the methods of synthesizing thereof are provided. The PE polymer product can have a density of from 0.922 to 0.940 g / cm3 and a water vapor transmission rate (WVTR) of 1.0 g-mil / 100 in2-day or less, where the PE polymer product comprises from 100 to 3,000 ppm of a nucleating agent. Balancing the barrier properties and mechanical properties, the PE polymer product can be suitable for various packaging applications.

Description

[0001]LINEAR POLYETHYLENE COMPOSITIONS WITH IMPROVED BARRIER PROPERTIES TECHNICAL FIELD The present disclosure relates generally to linear polyethylene (PE) polymer compositions, particularly to compositions with improved barrier properties. BACKGROUND ART Plastic films are widely used as packaging materials for foods. Flexible films, including multilayer films, are used to prepare bags, wrappers, pouches and other thermoformed materials. The permeability of these plastic films to gases (especially oxygen) and moisture is an important consideration during the design of a suitable food package. The permeability of linear polyethylene film to moisture is typically described by a “water vapor transmission rate” (or “WVTR”). In certain applications some vapor transmission is desirable—for example, to allow moisture out of a package which contains produce. The use of linear low-density polyethylene (LLDPE) which can be filled with calcium carbonate (to further increase vapor transmission) is common for this purpose. Conversely, for packages which contain crispy foods such as breakfast cereals or crackers, it is desirable to limit WVTR to very low levels to prevent the food from going stale. One approach to improve the barrier properties of LLDPE (e.g., lowering WVTR) is to combine a high-density polyethylene (HDPE) via blending (e.g., bimodal density distribution) and / or film layers. However, this approach can compromise the superior mechanical properties of LLDPE. Accordingly, there is still a need for new LLDPE compositions exhibiting a good balance of barrier properties and mechanical properties with good processability. SUMMARY OF INVENTION An embodiment described herein provides a linear polyethylene (PE) polymer product. The PE polymer product has a density of from 0.922 to 0.940 g / cm3and a water vapor transmission rate (WVTR) of 1.0 g-mil / 100 in2-day or less. The LLDPE polymer product comprises from 100 to 3,000 ppm of a nucleating agent. BRIEF DESCRIPTION OF DRAWINGS Figure 1 is an example process flow of the method of producing a linear polyethylene (linear PE) product in accordance with some embodiments. Figure 2 is gel permeation chromatographs (GPC) for linear PE in accordance with some embodiments (1P1-1P5). Figure 3 is gel permeation chromatographs (GPC) for linear PE in accordance with some embodiments (1P6-1P9). Figure 4 is differential scanning calorimetry (DSC) thermograms for linear PE in accordance with some embodiments (1P1-1P5). Figure 5 is a plot of the relationship between water vapor barrier property and density for linear PE products with and without a nucleating agent in accordance with some embodiments. Figure 6 is a plot of the relationship between oxygen barrier property and density for linear PE products with and without a nucleating agent in accordance with some embodiments. Figure 7 is a plot of the relationship between water vapor barrier property and elasticity (1% secant modulus) for linear PE products with and without a nucleating agent in accordance with some embodiments. Figure 8 is a plot of the relationship between oxygen barrier property and elasticity (1% secant modulus) for linear PE products with and without a nucleating agent in accordance with some embodiments. Figure 9 is a chart of 1% secant modulus for linear PE products with a nucleating agent in accordance with some embodiments. Figure 10 is a chart of puncture resistance for linear PE products with a nucleating agent in accordance with some embodiments. Figure 11 is a chart of tear resistance for linear PE products with a nucleating agent in accordance with some embodiments. Figure 12 is a chart of haze for linear PE products with a nucleating agent in accordance with some embodiments. Figure 13 shows gel permeation chromatographs (GPC) with FTIR for linear PE in accordance with other embodiments (2P1-2P5). DESCRIPTION OF EMBODIMENTS Embodiments described in this disclosure provide linear polyethylene (linear PE) compositions with improved barrier properties, balanced mechanical properties, and suppressed dusting characteristic. Also described are methods of synthesizing PE film products with these features. The density of the linear PE can be between 0.910 g / cm3and 0.925 g / cm3and classified as low-density PE (LDPE) according to ASTM D4976-12a (2020). In some embodiments, the density can be greater than 0.925 g / cm3and the linear PE can be seen as medium-density PE (MDPE). In various embodiments, the water vapor barrier and oxygen barrier properties are substantially improved without compromising the mechanical properties of the linear PE film products. In some embodiments, the improvement of the linear PE film product properties is achieved by combining a multi-reactor polymerization process with the addition of a nucleating agent during a film formation step. The linear PE in accordance with various embodiments advantageously exhibits better overall barrier properties (e.g., water vapor and / or oxygen) than other standard linear low- density polyethylene (LLDPE) films with the same range of density and melt index. In some embodiments, barrier properties are better than or comparable to PE films with higher densities (e.g., 0.926 g / cm3). At the same time, the linear PE can show better tear resistance and good secant modulus. Through experiments and simulations, it was demonstrated that the nucleating agent-containing linear PE films in accordance with some embodiments offer various advantages over current PE or other polymer films in packaging applications such as dry food packaging. Linear PE Composition and Characteristics In some embodiments, the linear PE described in this disclosure is characterized by an overall density generally classified as low-density PE (LDPE), such as a density of 0.925 g / cm3or less. The linear PE can have a density slightly above the standard LDPE range, e.g., about 0.935 g / cm3and classified as a medium-density PE (MDPE). In some embodiments, the density is from 0.922 to 0.940 g / cm3or 0.922 to 0.925 g / cm3. In some embodiments, the linear PE is a polymer blend with more than one PE fractions. In some embodiments, the linear PE also contains non-PE additive components. Accordingly, the linear PE can include a small fraction with a density higher than the standard upper limit of low-density PE (e.g., high density PE, > 0.940 g / cm3) as long as the overall density is kept within the ranges as described above. In some embodiments, the linear PE has relatively low melt index (I2) of 2.0 g / 10 min or less. In some embodiments, I2 is from 0.5 to 2.0 g / 10 min, for example, from 1.1 to 1.6 g / 10 min or from 1.3 to 2.0 g / 10 min. In some embodiments, I2is from 0.5 to 1.5 g / 10 min. In some embodiments, the linear PE has a melt flow ratio (I21 / I2) of from 32 to 95, for example, from 70 to 83. In some embodiments, the melt flow ratio is from 53 to 63. In some embodiments, the linear PE has a weight average molecular weight (Mw) of from 80,000 to 130,000. In some embodiments, Mw is from 80,000 to 115,000, for example, from 94,000 to 115,000, from 80,000 to 92,000, from 91,000 to 92,000, or from 92,000 to 100,000. In some embodiments, the linear PE has a number average molecular weight (Mn) of 30,000 or less, for example, 25,000 or less. In some embodiments, Mn is from 19,000 to 24,000. In some embodiments, the linear PE has a molecular weight distribution (Mw / Mn) of 6.0 or less, for example, from 2.0 to 6.0. In some embodiments, Mw / Mn is 5.7 or less, for example, from 4.7 to 5.7, or from 4.2 to 5.1. The linear PE described in this disclosure can further be processed via extrusion to form a film product including a nucleating agent. In some embodiments, the linear PE film product with the nucleating agent has a water vapor transmission rate (WVTR) of 1.0 g- mil / 100 in2-day or less, for example, 0.9 g-mil / 100 in2-day or less. In some embodiments, the WVTR is from 0.5 to 0.8 g-mil / 100 in2-day or from 0.7 to 0.9 g-mil / 100 in2-day, for example, from 0.8 to 0.9 g-mil / 100 in2-day. In some embodiments, the linear PE film product with the nucleating agent has an oxygen transmission rate (OTR) of 450 cm3-mil / 100 in2-day or less, for example, from 210 to 360 cm3-mil / 100 in2-day or from 300 to 450 cm3-mil / 100 in2-day. In some embodiments, the OTR is from 300 to 370 cm3-mil / 100 in2-day. Advantageously, the linear PE film product can exhibit such barrier properties without compromising the inherent mechanical properties of a linear low-density PE (LLDPE). In some embodiments, the linear PE film product has 1% secant modulus in machine direction (MD) of from 200 to 400 MPa, for example, from 290 to 360 MPa. In some embodiments, the linear PE film product has 1% secant modulus in transverse direction (TD) of from 200 to 500 MPa, for example, from 240 to 450 MPa. In some embodiments, the linear PE film product has a puncture resistance of 40 J / mm or greater. In some embodiments, the puncture resistance is from 40 to 70 J / mm, for example, from 50 to 65 J / mm. In some embodiments, the linear PE film product has a tear resistance of 50 g / mil or greater, for example, from 50 to 300 g / mil in MD. In some embodiments, the tear resistance in TD is 300 g / mil or greater, for example, from 300 to 600 g / mil. In some embodiments, the linear PE presents low hexene extractables of 2% or less, for example, 1% or less. In addition, despite the presence of a low Mw fraction in the linear PE, the linear PE can advantageously form a clean film without dusting during the film production. In some embodiments, the linear PE is formed as a copolymerization of ethylene and one or more comonomers. Examples of the monomers for copolymerization with ethylene include C3-20 mono- and di-olefins, for example C3-10 olefins. In some embodiments, the comonomer includes C3-10alpha olefins which are unsubstituted or substituted by up to two C1-6 alkyl radicals, C8-12 vinyl aromatic monomers which are unsubstituted or substituted by up to two substituents selected from the group consisting of C1-4alkyl radicals, C4-12straight chained or cyclic diolefins which are unsubstituted or substituted by a C1-4 alkyl radical. Illustrative non-limiting examples of such alpha-olefins are one or more of propylene, 1- butene, 1-pentene, 1-hexene, 1-octene and 1-decene, styrene, alpha methyl styrene, and the constrained-ring cyclic olefins such as cyclobutene, cyclopentene, dicyclopentadiene norbornene, alkyl-substituted norbornenes, and alkenyl-substituted norbornenes (e.g., 5- methylene-2-norbornene and 5-ethylidene-2-norbornene, bicyclo-(2,2,1 )-hepta-2,5-diene). In one embodiment, the comonomer is 1-octene. In some embodiments, the comonomer content in the linear PE is 5 mol% or less, for example, from 2 to 4 mol%. In some embodiments, the linear PE can have a flat, normal, or reverse comonomer distribution. In some embodiments, the linear PE composition is bimodal with two polymer fractions, a high and low molecular weight fraction. Two fractions can have different Mw, Mn, and branch frequency. The bimodal composition can be enabled by a multi-reactor polymerization process as described below, for example, where the first polymer fraction is primarily formed in a first reactor and the second polymer fraction is primarily formed in a second reactor. In some embodiments the linear PE composition contains detectable levels of long chain branching. Long chain branching, hereinafter “LCB”, is a well-known structural phenomenon in ethylene polymers to those of ordinary skill in the art. In the present disclosure, a long chain branch has a molecular weight equal to, or greater than, the entanglement molecular weight, Me. Meis a well-known concept in polymer physics (e.g., reported to be about 1 kg / mol for polyethylenes, see Fetters et al., Macromolecules 1999, 32, 6847). Presence of long chain branches in a sample can be detectable by comparing rheological test results with a comparative sample known to contain no long chain branches. Non-limiting examples of rheological test results include, flow activation energy (Ea), shear thinning or viscosity ratios, melt flow ratios (I21 / I2, I10 / I2, etc.), melt strength, etc. In some embodiments, the linear PE composition contains no or undetectable levels of long chain branching. Multi-Reactor Polymerization Process In some embodiments, a linear PE composition is prepared by a solution polymerization process using two or more reactors that operate under different polymerization conditions. This polymerization process can advantageously provide a uniform, in situ blend of the linear PE components. Solution processes for the (co)polymerization of ethylene to produce polyethylene (PE) are well known in the art. These processes are conducted in the presence of an inert hydrocarbon solvent typically a C5-12hydrocarbon which can be unsubstituted or substituted by a C1-4 alkyl group, such as pentane, methyl pentane, hexane, heptane, octane, cyclohexane, methylcyclohexane and hydrogenated naphtha. An example of a suitable solvent which is commercially available is “Isopar®E” (C8-12 aliphatic solvent, Exxon Chemical Co.). In some embodiments, the solution polymerization process uses at least two polymerization reactors operating under different conditions. For example, the first polymerization reactor can be operated at a lower temperature (“cold reactor”) than the second polymerization reactor. The polymerization temperature in the first reactor is from about 80°C to about 180°C in some embodiments, for example, from about 120°C to 160°C. The hot reactor can be operated at a higher temperature (up to about 220°C). In some embodiments, the pressure in each reactor is less than about 6,000 psi (about 42,000 kPa), and in one embodiment from about 2,000 psi to 3,000 psi (about 14,000-22,000 kPa). In some embodiments, the first fraction from the first reactor has an estimated branch frequency from 3 to 10 branch per 1000°C. In some embodiments, an estimated Mw is from 150,000 to 250,000, for example, from 184,000 to 220,000. In some embodiments, the second fraction from the second reactor has an estimated branch frequency from 8 to 19 branch per 1000°C. In some embodiments, an estimated Mw is from 10,000 to 90,000, for example, from 16,800 to 65,300. In some embodiments, an estimated Mn is from 8,400 to 32,000. In some embodiments, the estimated Mn is 11,000 or less. In some embodiments, the first fraction accounts for about 45 wt% of the total weight of the linear PE and the second fraction accounts for about 55 wt%. In one embodiment, the second fraction accounts for more than 55 wt%. In some embodiments, the polymerization is performed using a metallocene catalyst. In one or more embodiments, the metallocene catalyst includes a Ti-, Hf-, or Zn-based phosphinimine catalyst. In some embodiments, the linear PE composition is synthesized by a multi reactor solution polymerization process using a metallocene catalyst in a first reactor and a second catalyst in a second reactor. In one or more embodiments, the metallocene catalyst includes Hf and the second catalyst includes a Ziegler-Natta catalyst. Extrusion With the Addition of a Nucleating Agent After the polymerization, the linear PE can be further processed into a film product. In some embodiments, the linear PE film products are prepared by “blown film” extrusion of a polymer melt, in which the plastic is melted in an extruder downstream from the polymerization reactors, then forced through an annular die. The extrudate from the annular die is subjected to blown air, thus forming a plastic bubble. The use of multiple extruders and concentric dies permits multilayer structures to be co-extruded by the blown film process. The “product” from this operation is “barrier film” which is collected on rolls and shipped to the manufacturers of food packaging. In some embodiments, the nucleating agent is added to the plastic melt during the extrusion step after the polymerization step, e.g., after deactivating the polymerization catalyst. As shown in the Examples below, the addition of the nucleating agent improved the barrier properties of the linear PE film products. The term “nucleating agent”, as used herein, is meant to convey its conventional meaning to those skilled in the art of preparing nucleated polyolefin compositions, namely an additive that changes the crystallization behavior of a polymer as the polymer melt is cooled. Nucleating agents are widely used to prepare classified polypropylene and to improve the molding characteristics of polyethylene terephthalate (PET). There are two major families of nucleating agents, namely “inorganic” (e.g., small particulates, especially talc or calcium carbonate) and “organic”. High performance, organic nucleating agents which have a very high melting point have recently been developed. These nucleating agents are sometimes referred to as “insoluble organic” nucleating agents—to generally indicate that they do not melt disperse in polyethylene during polyolefin extrusion operations. In general, these insoluble organic nucleating agents either do not have a true melting point (i.e., they decompose prior to melting) or have a melting point greater than 300°C or, alternatively stated, a melting / decomposition temperature of greater than 300°C. The amount of nucleating agent used is comparatively small, in some embodiments, ranging from 100 to 3,000 parts by million per weight (ppm) (based on the weight of the polyethylene) so it will be appreciated by those skilled in the art that some care must be taken to ensure that the nucleating agent is well dispersed. Examples of nucleating agents include the cyclic organic structures disclosed in U.S. Pat. No. 5,981,636 (and salts thereof, such as disodium bicyclo [2.2.1] heptene dicarboxylate); the saturated versions of the structures disclosed in U.S. Pat. No. 5,981,636 (as disclosed in U.S. Pat. No. 6,465,551; Zhao et al., to Milliken); the salts of certain cyclic dicarboxylic acids having a hexahydrophtalic acid structure (or “HHPA” structure) as disclosed in U.S. Pat. No. 6,559,971 (Dotson et al., to Milliken); and phosphate esters, such as those disclosed in U.S. Pat. No. 5,342,868 and those sold under the trade names NA-11 and NA-21 by Asahi Denka Kogyo. Specific examples include cyclic dicarboxylates and the salts thereof, especially the divalent metal or metalloid salts, (particularly, calcium salts) of the HHPA structures disclosed in U.S. Pat. No. 6,559,971. For clarity, the HHPA structure generally comprises a ring structure with six carbon atoms in the ring and two carboxylic acid groups which are substituents on adjacent atoms of the ring structure. The other four carbon atoms in the ring can be substituted, as disclosed in U.S. Pat. No. 6,559,971. In some embodiments, the nucleating agent is 1,2-cyclohexanedicarboxylic acid, calcium salt (CAS registry number 491589-22-1, commercially available as HPN®20E from Milliken). Figure 1 is an example process flow of the method of producing a linear low-density polyethylene (linear PE) product in accordance with some embodiments. In some embodiments, a process 100 of synthesizing the linear PE product starts with forming a first polymer solution by polymerizing ethylene in a solvent in a first stirred polymerization reactor at a temperature of from 80 to 200°C and a pressure of from 1,500 to 5,000 psi in the presence of a first catalyst (block 110), followed by passing the first polymer solution into a second stirred polymerization reactor (block 120). Subsequently, a second polymer solution can be formed from the first polymer solution by polymerizing ethylene in the second stirred polymerization reactor in the presence of a second catalyst (block 130). The second polymer solution is then phase separated to recover a linear PE polymer (block 140), which can then pass into an extruder to form the linear PE polymer product from the linear PE polymer (block 150). The linear PE polymer can have a density of from 0.922 to 0.940 g / cm3and the final linear PE polymer product can have a water vapor transmission rate (WVTR) of 1.0 g-mil / 100 in2-day or less. Although the specific details will vary from manufacturer to manufacturer, it will be readily appreciated that the film needs to have a balance of physical properties for food packaging. In addition to low WVTR, it is desirable for the film to “seal” well and to have sufficient impact strength and stiffness (or film “modulus”) to allow easy handling of the package. Multilayer coextrusions are often used to achieve this balance of properties, with 3- and 5-layer coextrusions being well known. Sealant layers can be prepared with ethylene- vinyl acetate (EVA) ionomers (such as those sold under the trademark SURLYN®by E.I. DuPont), very low-density polyethylene (polyethylene copolymers having a density of less than 0.910 grams per cubic centimeter) and blends with small amounts of polybutene. It is known to use sealant compositions in both “skin” layers of a coextrusion or in only one of the skin layers. Linear PE Film Applications The linear PE in accordance with various embodiments of this disclosure can potentially replace some of the film products currently used in various packaging applications where a good balance of mechanical strength and barrier properties is required. The linear PE can be used as a polymer blend component for certain applications. For example, the linear PE can substitute one or more of the components currently used in easy- open peelable seals applications (e.g., ethylene-vinyl acetate (EVA) and polybutenene-1). In some embodiments, the linear PE film demonstrates an acceptable peelable range of seal force can be achieved using a blend of one linear PE and polybutenene-1. The linear PE can be used for a single layer film product or multi-layer film products, where one or more layers can be the linear PE. For example, the linear PE can be applied in packaging for dry foods such as crackers and breakfast cereals. Simulations using NOVA Chemicals’ BONFIRE®Film Development Platform were performed to further evaluate the film performance of the linear PE film product in three potential applications. First, the substitution of layer B (FP120 blend resin) in a three-layer dry food packaging (e.g., cereal bags) with exemplary linear PE films was simulated. The simulation results showed about 28% reduction in WVTR and about 20% reduction in OTR with improvements in tear resistance and secant modulus. Second, the substitutions of a layer (layer B or D) in a five-layer liquid packaging film structure with exemplary linear PE films also showed significant reduction in OTR (about 18% for layer B; about 8% for layer D) and in WVTR (about 13% for both cases). Third, the substitutions of one or more layers (layer C, or layers B and D) in a five- layer poultry film structure with exemplary linear PE films were simulated. The simulation results showed about 11% reduction in WVTR for both cases. Other than in the operating examples or where otherwise indicated, all numbers or expressions referring to quantities of ingredients, reaction conditions, etc. used in the specification and claims are to be understood as modified in all instances by the term “about”. Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that can vary depending upon the desired properties, which the present disclosure desires to obtain. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the disclosure are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical values, however, inherently contain certain errors necessarily resulting from the standard deviation found in their respective testing measurements. In addition, it should be understood that any numerical range recited herein is intended to include all sub-ranges subsumed therein. For example, a range of “1 to 10” is intended to include all sub-ranges between and including the recited minimum value of 1 and the recited maximum value of 10; that is, having a minimum value equal to or greater than 1 and a maximum value of equal to or less than 10. Because the disclosed numerical ranges are continuous, they include every value between the minimum and maximum values. Unless expressly indicated otherwise, the various numerical ranges specified in this application are approximations. Additional advantages and modifications will readily appear to those skilled in the art. The invention in its broader aspects is therefore not limited to the specific details, representative apparatus and method, and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the scope of the general inventive concept. EXAMPLES Single Catalyst The linear PE samples were produced in a pilot-scale, three-rector, in-series solution- phase polymerization process. Example of this multi-reactor polymerization with catalysts as well as examples of polymerization catalysts are described in published U.S. Pat. Appl. Pub. No.2019 / 0135958 and U.S. Pat. Appl. Pub. No.2018 / 0305532A1, the disclosures of which are incorporated herein by reference. In brief, in the “in-series” reactor system the exit stream from a first polymerization reactor (R1) flows directly into a second polymerization reactor (R2). The R1 pressure was from about 14 MPa to about 18 MPa; while R2 was operated at a lower pressure to facilitate continuous flow from R1 to R2. Both R1 and R2 were continuously stirred reactors (CSTRs). The third reactor, R3 was a tubular reactor configured in series with the second reactor, R2 (i.e., the contents of reactor 2 flowed into reactor 3). The process was operated continuously by feeding fresh process solvent, ethylene, 1-octene and hydrogen to the first and second reactors and in the removal of product. Methylpentane was used as the process solvent (a commercial blend of methylpentane isomers). The volume of the first CSTR reactor (R1) was 3.2 gallons (12 L), and the volume of the second CSTR reactor (R2) was 5.8 gallons (22 L). The volume of the tubular reactor (R3) was 4.755 gallons (18 L). Monomer (ethylene) and comonomer (1-octene) were purified prior to addition to the reaction using conventional feed preparation systems (such as contact with various absorption media to remove impurities such as water, oxygen and polar contaminants). In the Example of single catalyst polymerization a Ti-based phosphinimine single site catalyst formulation was used and fed to a first reactor and a second reactor along with fresh reactants. The Ti-based phosphinimine single site catalyst formulation included the following components: component C, cyclopentadienyl tri(tertiary butyl)phosphinimine titanium dichloride {Cp[(t-Bu)3PN]TiCl2}; component M, methylaluminoxane (MMAO-07); component B, trityl tetrakis(pentafluoro-phenyl)borate and; component P, 2,6-di-tert-butyl- 4-ethylphenol. The following catalyst component solvents were used: methylpentane for components M and P; and xylene for component C and B. The efficiency of the Ti-based phosphinimine single site catalyst formulation was optimized by adjusting the quantity of component C added to R1 and R2, the mole ratios of the catalyst components—e.g., [M] / [C], [P] / [M] and [B] / [C]—in each of R1 and R2. In samples 1P1 through 1P9, the concentration of component C added to R1 was about 0.1 ppm and the concentration of component C added to R2 was from about 0.2 to 0.4 ppm. In samples 1P1 through 1P9, the mole ratio of component M to component C in R1 and R2 were 100 and 25, respectively. In samples 1P1 through 1P9, the mole ratio of component P to component M in R1 and R2 was about 0.3. In samples 1P1 through 1P9, the mole ratio of component B to component C in R1 and R2 was about 1.3. The catalyst components inlet temperature was ranging from about 20 to about 30°C in R1 and from about 30 to about 35°C in R2. No catalyst or fresh reactants were added to the third reactor (R3). Two series of samples with different additives were examined. Five samples for Series I and four samples for Series II with different polymer architecture and melting temperature profile were summarized below. The samples in the Series I were produced at a target density of 0.922 g / cm3and the samples in the Series II were produced at a target density of 0.935 g / cm3or 0.922 g / cm3. In both Series, the total amount of ethylene supplied to the process was portioned or split between the two reactors R1 and R2. This operational variable (ethylene split or ES) is herein defined according to the weight percent of ethylene injected in R1 and R2, respectively; with the proviso that ESR1+ ESR2= 100% and ESR3= 0%. Comonomer (1-octene) was also added to the continuous solution polymerization process and was proportioned or split between R1 and R2. This operational variable (octene split or OS) is herein defined according to the weight percent of 1-octene comonomer that was injected in R1 and R2, respectively; with the proviso that OSR1+ OSR2= 100% and OSR3= 0%. In samples 1P1 through 1P5, the ethylene split to the reactors R1 and R2— ESR1 / ESR2—were all set at 45% / 55%. In samples 1P1 through 1P5, the 1-octene split to the reactors R1 and R2—OSR1 / OSR2—were 80% / 20%, 100% / 0%, 91% / 9%, 80% / 20% and 20% / 80%, respectively. In samples 1P6 through 1P9, the ethylene split to the reactors R1 and R2—ESR1 / ESR2—were 45% / 55%, 45% / 55%, 45% / 55% and 40% / 60%. In samples 1P6 through 1P9, the 1-octene split to the reactors R1 and R2—OSR1 / OSR2—were 80% / 20%, 80% / 20%, 80% / 20% and 70% / 30%, respectively. In operating the continuous solution polymerization process in samples 1P1 through 1P9, ethylene, 1-octene and process solvent were combined to form a first fresh feed stream RF1 and then injected into the first reactor R1. Similarly, in operating the continuous solution polymerization process in samples 1P1 through 1P9, ethylene, 1-octene and process solvent were combined to form a second fresh feed stream RF2 and then injected into the second reactor R2. In samples 1P1 through 1P9, the temperature of the first fresh feed stream was 30°C. In samples 1P1 through 1P9, the temperature of the second fresh feed stream RF2 was 50.0°C, 70.2°C, 70.2°C, 70.0°C and 39.9°C, respectively. In operating the continuous solution polymerization process in samples 1P1 through 1P5, the second reactor R2 had a mean temperature (TR2) greater than the mean temperature of the first reactor R1 (TR1). To be clear, samples 1P1 through 1P5 were operated at a TR1 / TR2of 136.0°C / 194.6°C, 144.9°C / 190.0°C, 140.0°C / 190.0°C, 139.9°C / 199.9°C and 148.3°C / 195.9°C. In operating the continuous solution polymerization process in samples 1P1 through 1P5, the third reactor R3 had an exit temperature (TR3exit) slightly greater than the mean temperature of the second reactor R2 (TR2)—e.g., 0°C < TR3exit – TR2≲ 5°C. In samples 1P6 through 1P9 were operated at a TR1 / TR2of 148.7°C / 201.5°C, 147.5°C / 201.9°C, 133.6°C / 195.9°C and 141.3°C / 194.9°C. In samples 1P6 through 1P9, the third reactor R3 had an exit temperature (TR3exit) less than the mean temperature of the second reactor R2 (TR2)— e.g., –15°C ≲ TR3exit – TR2< 0°C. In operating the continuous solution polymerization process shown in samples 1P1 through 1P5, the total amount of ethylene polymerized in each reactor is monitored. The term QR1refers to the percent of the ethylene added to R1 that was polymerized by the catalyst formulation. Similarly, QR2and QR3represent the percent of the ethylene added to R2 and residual ethylene flown into R3 from R1 and R2 that were polymerized. Samples 1P1 through 1P5 had a QR1 / QR2 / QR3of 82.0% / 83.2% / 41.9%, 82.9% / 83.0% / 54.3%, 72.1% / 72.0% / 33.5%, 72.2% / 72.0% / 26.0% and 82.0% / 83.0% / 41.2%, respectively. Samples 1P6 through 1P9 had a QR1 / QR2 / QR3of 78.3% / 75.7% / 23.6%, 77.4% / 74.5% / 22.4%, 82.0% / – / 0.0% and 77.0% / – / polymerization process—i.e., QT= 100 × [weight of ethylene in the ethylene polymer composition] / ([weight of ethylene in the ethylene polymer composition] + [weight of unreacted ethylene]—was also monitored. Samples 1P1 through 1P5 had a QTof 90.2%, 92.2%, 81.4%, 79.3% and 90.0%, respectively. Samples 1P6 through 1P9 had a QTof 81.4%, 80.3%, 81.4%, 90.0% and 86.0%, respectively. In operating the continuous solution polymerization process for preparing samples 1P1 through 1P5, hydrogen was injected into the first reactor R1 and the second reactor R2 to control (reduce) the molecular weight of the polymerized species. To be specific, in samples 1P1 through 1P5, the weight percent of hydrogen in the inlet stream of R1 and R2 (H2R1 / H2R2) were 0.69 / 13.00, 0.50 / 1.00, 0.50 / 11.58, 0.70 / 16.83 and 0.61 / 15.00, respectively. In samples 1P6 through 1P9, the weight percent of hydrogen in the inlet stream of R1 and R2 (H2R1 / H2R2) were 0.90 / 16.81, 0.90 / 18.81, 0.69 / 13.00 and 0.56 / 13.98, respectively. CSTR reactors R1 and R2 were continuously stirred by a stirring assembly which included a motor external teach reactor and an agitator within each reactor. In samples 1P1 through 1P5, the rate of agitation for R1 and R2 were 500 rpm and 260 rpm, respectively. In samples 1P6 through 1P9, the rate of agitation for R1 / R2 were 500 rpm / 260 rpm, 500 rpm / 260 rpm, 447 rpm / 260 rpm and 500 rpm / 260 rpm, respectively. Polymerization in the continuous solution polymerization process was terminated by adding a catalyst deactivator to the stream exiting the tubular reactor (R3). The catalyst deactivator used was octanoic acid (caprylic acid), commercially available from P&G Chemicals, Cincinnati, OH, U.S.A. The catalyst deactivator was added such that the moles of fatty acid added were 50% of the total molar amount of catalytic metal and aluminum added to the polymerization process; to be clear, the moles of octanoic acid added = 0.5 × (moles titanium + moles aluminum). A two-stage devolatilization process was employed to recover the linear PE samples 1P1 through 1P5 from the process solvent, i.e., two vapor / liquid separators were used, and the second bottom stream (from the second V / L separator) was passed through a gear pump / pelletizer combination. The gear pump was a VACOREX®45 / 45 pump with 191 liter per hour capacity which was steam jacketed with 270# steam. The ethylene polymer composition leaving the gear pump was then passed through a 4” diameter static mixer before entering the pelletizer where the ethylene polymer composition was forced through the holes in the die plate top down. There were 32 holes on the die with a hole diameter of 0.125”. The aspect ratio (i.e., length-to-diameter ratio) for each hole was 6.3:1 and the die had a thickness of 1.63” and a diameter of 12”. There were 6 cutter knives—8.6878” OD sweep and 6.2418 ID sweep—located on the side of the die that faced the cooling water system. There were internal heating channels within the die plate and die body and plate were heated with 600# or 270# steam. Cooling water system had a temperature range of from 10 to 80°C and a flow of 7500–9500 kg / h. DHT®-4V (hydrotalcite), supplied by Kyowa Chemical Industry Co. LTD, Tokyo, Japan was used as a passivator, or acid scavenger, in the continuous solution process. A slurry of DHT-4V in process solvent was added prior to the first V / L separator. Prior to pelletization, the linear PE samples 1P1 through 1P5 were stabilized by adding 500 ppm of IRGANOX®1076 (a primary antioxidant) and 500 ppm of IRGAFOS®168 (a secondary antioxidant), based on weight of the linear PE sample. Antioxidants were dissolved in process solvent and added between the first and second V / L separators. For both Series I and Series II, film products with nucleating agent were obtained by adding 3 weight percent of a masterbatch of 4 weight percent of HYPERFORM®HPN®20E nucleating agent in an ethylene homopolymer carrier resin to the extruder during the film production step to reach a target nucleating agent content of 1,200 ppm in the linear PE. Various materials properties and film performance of the exemplary linear PE samples were determined or simulated based on standard methods described below. The density was determined by ASTM D 792 for plaques which were compression molded at a cooling rate of 15 ± 2°C per minute according to ASTM D4703. The weight average molecular weight (Mw) and number average molecular weight (Mn) were determined by gel permeation chromatography (GPC) on polymer solutions having a concentration of from 1 to 3 mg / ml which were prepared by heating the polymer in 1,2,4-trichlorobenzene (TCB) and rotating on a wheel for 4 hours at 150°C in an oven. An antioxidant (2,6-di-tert-butyl-4-methylphenol (BHT)) was added to the polymer solution in order to stabilize the polymer against oxidative degradation. The BHT concentration was 250 ppm. Polymer solutions were chromatographed at 140°C on a PL 220 high-temperature chromatography unit equipped with four SHODEX®columns (HT803, HT804, HT805 and HT806) using TCB as the mobile phase with a flow rate of 1.0 ml per minute, with a differential refractive index (DRI) as the concentration detector. BHT was added to the mobile phase at a concentration of 250 ppm to protect GPC columns from oxidative degradation. The sample injection volume was 200 μl. The GPC columns were calibrated with narrow distribution polystyrene standards. The polystyrene molecular weights were converted to polyethylene molecular weights using the Mark-Houwink equation, as described in the ASTM standard test method D6474-12 (December 2012). The GPC raw data were processed with the CIRRUS®GPC software, to produce molecular weight averages Mn and Mw, and polydispersity index, Mw / Mn. A high temperature GPC equipped with an online FTIR detector (GPC-FTIR) was used to measure the comonomer content as the function of molecular weight. In the GPC- FTIR procedure, polymer solutions were prepared by heating 2 to 4 mg / ml of the polymer sample in 1,2,4-trichlorobenzene (TCB) and rotating on a wheel for 4 hours at 150°C in an oven. An antioxidant, 2,6-di-tert-butyl-4-methylphenol (BHT), was added to the mixture in order to stabilize the polymer against oxidative degradation. The BHT concentration was 250 ppm. Sample solutions were chromatographed at 140°C on a Waters GPC 150C chromatography unit equipped with four SHODEX columns (HT803, HT804, HT805 and HT806) using TCB as the mobile phase with a flow rate of 1.0 ml / minute, with a FTIR spectrometer and a heated FTIR flow through cell coupled with the chromatography unit through a heated transfer line as the detection system. BHT was added to the mobile phase at a concentration of 250 ppm to protect SEC columns from oxidative degradation. The sample injection volume was 300 µl. The raw FTIR spectra were processed with OPUS FTIR software, and the polymer concentration and methyl content were calculated in real time with the Chemometric Software (PLS technique) associated with the OPUS. Then the polymer concentration and methyl content were acquired and baseline-corrected with the CIRRUS GPC software. The SEC columns were calibrated with narrow distribution polystyrene standards. The polystyrene molecular weights were converted to polyethylene molecular weights using the Mark-Houwink equation, as described in the ASTM standard test method D6474-12. The comonomer content was calculated based on the polymer concentration and methyl content predicted by the PLS technique as described in Paul J. DesLauriers, Polymer 43, pages 159-170 (2002); herein incorporated by reference. The GPC-FTIR method measures total methyl content, which includes the methyl groups located at the ends of each macromolecular chain, i.e., methyl end groups. Thus, the raw GPC-FTIR data must be corrected by subtracting the contribution from methyl end groups. To be clear, the raw GPC- FTIR data overestimates the amount of short chain branching (SCB) and this overestimation increases as molecular weight decreases. In this disclosure, raw GPC-FTIR data was corrected using the 2-methyl correction. At a given molecular weight (M), the number of methyl end groups (NE) was calculated using the following equation: NE = 28000 / M, and NE (M dependent) was subtracted from the raw GPC-FTIR data to produce the SCB per 1000 carbon atoms (2-Methyl corrected) GPC-FTIR data. The melt index (I2) was determined according to ASTM D 1238 and expressed in grams of polyethylene which flow during the 10-minute testing period, or “gram / 10 minutes”. The comonomer content was determined was determine by FTIR and in mole percent (mol%). The FTIR test was completed according to ASTM D6645, employing a compression molded polymer plaque and a Thermo-Nicolet 750 Magna-IR Spectrophotometer. The polymer plaque for the FTIR test was prepared using a compression molding device (Wabash-Genesis Series press) according to ASTM D4703. Hexane extractables was determined according to the Code of Federal Registration 21 CFR § 177.1520 Para (c) 3.1 and 3.2; wherein the quantity of hexane extractable material in a film is determined gravimetrically. Elaborating, 2.5 grams of 3.5 mil (89 μm) monolayer film was placed in a stainless steel basket, the film and basket were weighed (wi), while in the basket the film was: extracted with n-hexane at 49.5°C for two hours; dried at 80°C in a vacuum oven for 2 hours; cooled in a desiccator for 30 minutes; and weighed (wf). The percent loss in weight was reported as the percent hexane extractables (wC6) according to wC6= 100 × (wi−wf) / wi. The barrier properties of the prepared films were characterized by measuring transmission rates of water and oxygen. Water Vapor Transmission Rate (“WVTR”, expressed as grams of water vapor transmitted per 100 square inches of film per day at a specified film thickness (mils), or g / 100 in2 / day) was measured in accordance with ASTM F1249-90 with a PERMATRAN-W®3 / 33 at conditions of 100°F (37.8°C) and 100% relative humidity. The oxygen vapor transmission rate (OTR) was determined according to ASTM D3985 using an OX-TRAN®2 / 20 instrument. The test instrument had two test cells (A and B) and each sample was analyzed in duplicate. The OTR result reported was the average of the results from the two test cells (A and B). The test was carried out at a temperature of 23°C and at a relative humidity of 0%. The sample area used for testing was 100 cm2. The carrier gas used was 2% hydrogen gas in a balance of nitrogen gas and the test gas Is ultra-high purity oxygen. Further, various other properties were characterized as follows. The haze was determined according to ASTM D 1003. Gloss was determined according to ASTM D 2457. The tear resistance was determined according to ASTM D 1922. Secant moduli in MD and TD directions were measured using a conventional Instron tensile tester equipped with a 200 lbf load cell. Strips of monolayer film samples were cut for testing with following dimensions: 14 inch long, 1 inch wide and 1 mil thick; ensuring that there were no nicks or cuts on the edges of the samples. Film samples were cut in both the machine direction (MD) and the transverse direction (TD) and tested. The thickness of each film was accurately measured with a hand-held micrometer and entered along with the sample name into the Instron software. Samples were loaded in the Instron with a grip separation of 10 inch and pulled at a rate of 1 inch / min generating the strain-strain curve. The 1% secant modulus was calculated using the Instron software according to the slope of a line drawn between two points on the stress-strain curve (i.e., the secant line). The first point on the stress-strain curve was the origin, i.e., the point that corresponded to the origin (the point of zero percent strain and zero stress); and the second point on the stress-strain curve was the point that corresponded to a strain of 1%. Given these two points the 1% secant modulus was calculated and expressed in terms of force per unit area (MPa). In addition, grease barrier properties were measured using the method by Falla (Falla et al., “Multilayer Polyethylene Films Having Grease Resistant Properties.” 2017). Briefly, the linear PE sample was placed on top of a fluorescent thin layer chromatography plate. A stainless-steel ring was then placed on top of the sample. The grease was placed inside the ring and a 2 kg metal weight / plug was placed on top of the sample. The assembly was put into an oven for accelerated testing. After 48 h at 60°C, the plate with the sample was photographed in a viewing box with an ultraviolet (UV) light. The grease absorbs light at 254 nm and appears as dark regions on the plate in the photograph. An imaging software was used to convert the dark regions into gray scale, with 0 being no grease and 100 total coverage. Further, dusting characteristic was examined as follows: (1) fixing a dark colored Velcro hoop tape as test swatch on a stationery mount; (2) drawing a quantity of the linear PE samples across the test swatch under constant tension conditions for a fixed period of time; (3) observing the amount of the abraded material (dust) which is deposited on the test swatch; and (4) quantifying the area of coverage of dust on the test swatch by image analysis. All samples for Series I were produced with a similar crystallinity at around 47%. For film property characterization (e.g., barrier properties), a monolayer blown film (1.5 mil) was prepared and used for each measurement. Blown films were generated by using a 2.5-inch Gloucester blown film line (L / D = 24) with a die diameter of 4-inch. A set of fixed process conditions of a die gap of 35 mils (0.0889 cm), a blow-up ratio (BUR) of 2.5, a frost line height of about 24 inches, and an output rate of 100 lbs / hr was used for all films prepared from the linear PE samples of Series I and Series II. All samples with the nucleating agent contained 3 weight percent of a master batch of 4 weight percent HYPERFORM HPN 20E in an ethylene homopolymer carrier resin to reach a target nucleating agent content of 1,200 ppm. To avoid melt fracture, all samples contained 2 weight percent of a process aid masterbatch which was a 5 weight percent masterbatch of 3M®DYNAMAR®FX 5920A in an LLDPE carrier resin to reach a target process aid content of 1000 ppm. The linear PE samples were dry blended with the process aid masterbatch, or process aid masterbatch and the nucleating agent masterbatch prior to the extrusion step using a WSB-241-T MAGUIRE blender. The effect of the addition of nucleating agent on the resulting barrier properties was examined by comparing the samples with and without the nucleating agent. Table 1. Linear PE Polymer Material Properties (Series I) Product 1P1 1P2 1P3 1P4 1P5 Catalyst Ti-based phosphinimine catalyst (both reactors) Density (g / cm3) 0.922 0.922 0.922 0.925 0.922 Melt Index (I2) (g / 10 min) 1.65 1.18 0.86 1.55 1.13 Melt Flow Ratio (I21 / I2) 70.82 32.04 75.00 81.94 82.74 Comonomer Cont. (mol%) 2.8 2.2 2.4 2.9 2.6 Weight ave. mol. weight 96,007 94,871 112,778 98,738 95,647 (Mw) (g / mol) Number ave. mol. weight 19,946 33,562 31,424 19,335 20,025 (Mn) (g / mol) Mw / Mn 5.67 2.83 3.59 5.11 4.78 Hexene Extractables (%) 0.85 0.28 0.42 2.00 0.85 Table 2. Barrier and Optical Properties of Linear PE Film with Nucleating Agent (NA) (Series I) Product 1P1 1P2 1P4 1P5 1P5 Water Vapor Transmission 0.979 1.051 1.055 1.206 0.999 Rate – no NA (WVTR) (g-mil / 100 in2-day) WVTR – with NA 0.741 0.888 0.960 0.806 0.728 (g-mil / 100 in2-day) Oxygen Transmission Rate 442.35 460.50 476.10 586.72 440.10 (OTR) – no NA (cm3-mil / 100 in2-day) OTR–with NA 315.00 363.52 400.48 419.05 332.70 (cm3-mil / 100 in2-day) 45º Gloss – with NA 44.5 63.1 17.2 22.2 19.2 Total Haze – with NA (%) 16.7 9.5 36.6 31.1 33.1 Internal Haze – with NA(%) 4.2 3.1 3.9 5.1 3.9 1% Secant Modulus (MD) – 357.7 348.7 338.6 356.2 320.4 with NA (MPa) Energy at Break in Puncture 46.8 55.0 57.6 41.9 48.8 Test – with NA (J / mm) Table 3. Linear PE Polymer Material Properties (Series II) Product 1P6 1P7 1P8 1P9 Catalyst Ti-based Phosphinimine Catalyst (Both Reactors) Density (g / cm3) 0.935 0.936 0.923 0.923 Melt Index (I2) (g / 10 min) 1.26 1.17 1.46 1.71 Melt Flow Ratio (I21 / I2) 47.24 53.66 65.64 95.01 Comonomer Cont. (mol%) 1.2 1.2 2.5 2.6 Weight ave. mol. weight 99,930 106,348 92,875 91,561 (Mw) (g / mol) Number ave. mol. weight 24,028 20,875 19,455 19,099 (Mn) (g / mol) Mw / Mn 4.16 5.09 4.77 4.79 Hexene Extractables (%) 0.21 0.17 n.d. 0.47 Table 4. Barrier and Optical Properties of Linear PE Film with Nucleating Agent (NA) (Series II) Product 1P6 1P7 1P8 1P9 Water Vapor Transmission 0.718 0.698 1.008 0.957 Rate – no NA (WVTR) (g-mil / 100 in2-day) WVTR – with NA 0.533 0.519 0.782 0.704 (g-mil / 100 in2-day) Oxygen Transmission Rate 294.75 298.95 474.15 445.95 (OTR) – no NA (cm3-mil / 100 in2-day) OTR–with NA 218.85 211.20 356.10 333.15 (cm3-mil / 100 in2-day) 45º gloss – with NA 31.1 28.0 35.0 25.2 Total Haze – with NA (%) 21.7 25.3 19.9 26.8 Internal Haze – with NA(%) 4.6 4.9 4.5 4.6 1% Secant Modulus (MD) – 391.0 436.9 287.5 295.4 with NA (MPa) Energy at Break in Puncture 36.7 38.6 45.0 45.8 Test – with NA (J / mm) Figure 2 is gel permeation chromatographs (GPC) for linear PE samples 1P1-1P5. Figure 3 is GPC for linear PE samples 1P6-9. Figure 4 is differential scanning calorimetry (DSC) thermograms for linear PE samples 1P1-1P5. The Mw, Mn, and Mw / Mn were generally within the range that is applicable for various PE applications. In Figures 2 and 3, the samples except sample 1P2 exhibited a bimodal Mw distribution, while in sample 1P2 it had a broader distribution having a shoulder to higher Mw without a clear distinction. All samples presented an increase in Tc onset with the addition of nucleating agent, confirming the nucleation. Meanwhile, in Figure 4, varying DSC cooling thermograms suggested a variety of populations of crystals among the samples. As summarized in Table 1, the density was in the range from 0.922 to 0.925 g / cm3across the samples for Series I, within the range of low-density polyethylene (LDPE). Further, the melt index (I2) was maintained at a relatively low level (e.g., < 2 g / 10 min) for all the samples, which is advantageous in blown film application. The melt flow ratio ranges from 32 to 83. In addition, the samples exhibited less than 2% of hexene extractables. On the other hand, for Series II, as summarized in Table 3, the density was in the range from 0.923 to 0.936 g / cm3, which overlaps the LDPE range (0.922 to 0.925 g / cm3) as well as the MDPE range (0.925 to 0.940 g / cm3). I2was maintained at a relatively low level (e.g., < 2 g / 10 min) for all the samples, while the melt flow ratio ranged from 47 to 95. In addition, the samples exhibited less than 0.5% of hexene extractables. Figure 5 is a plot of the relationship between water vapor barrier property and density for linear PE products with and without a nucleating agent in accordance with some embodiments. Figure 6 is a plot of the relationship between oxygen barrier property and density for linear PE products with and without a nucleating agent in accordance with some embodiments. In Tables 2 and 4, both water vapor barrier property and oxygen barrier property were improved by the addition of the nucleating agent. The water vapor transmission rate (WVTR) was reduced by about 15-33% for Series I and about 22-26% for Series II, and the oxygen transmission rate (OTR) by about 16-29% for Series I and about and 25-29% for Series II. Further illustrated in Figures 5 and 6, these barrier properties were comparable with or better than some reference samples with higher densities in the range of medium-density PE (MDPE) and high-density PE (HDPE). Grease barrier property of sample 1P5 was evaluated. The area percentile of grease permeance was 45% without the nucleating agent, while 1.5-mil blown films prepared from commercially-available LLDPE (NOVAPOL®PF-Y827-FP) and HDPE (SURPASS®HPs167‐AB), and a 48-gauge, corona-treated, oriented polyethylene terephthalate (PET) film showed the area percentile of 19% (LLDPE), 7% (HDPE), and 0.6% (PET), respectively. The addition of the nucleating agent to the sample 1P5 substantially improved the grease barrier property and the area percentile was reduced to 15%, at a comparable level with the commercial LLDPE films. Figures 7-8 show the relationship between barrier properties and elasticity (1% secant modulus) for linear PE products (Series I). Figure 9 summarizes 1% secant modulus in MD and TD of the linear PE products with a reference PE standard film for comparison. As shown in Figures 7-9, 1% secant modulus was generally comparable to the reference PE standard films while exhibiting better water (Figure 7) or oxygen (Figure 8) barrier properties. The results show that the addition of the nucleating agent improved not only the barrier properties but also the 1% secant modulus in MD (320-358 MPa for Series I and 288-437 MPa for Series II). Figures 10-11 show puncture resistance and tear resistance for linear PE products with the nucleating agent, respectively. Samples for Series I (1P1-1P5) showed better puncture resistance (41.9-57.6 J / mm) than the reference (33.8 J / mm) (Table 2 and Figure 10). Further, all samples for Series I showed better tear resistance than the reference in both MD and TD (Table 2 and Figure 11). Figure 12 is a chart of haze for linear PE products with the nucleating agent. In Figure 12, the total haze was constantly higher than the reference (8.85%), while the internal haze was at a comparable level (3.1-5.1%). The addition of the nucleating agent also resulted in reduction in haze (about 16-41%) and 1% secant modulus (3-23% increase in MD and 22- 46% in TD). In addition, no dusting was observed during the film production step. In general, a low Mw fraction of PE can migrate to the film surface increasing the potential for film dusting, delamination, and printing issues. However, such issues did not occur in the linear PE samples despite its considerable amount of low Mw fraction. Although not wishing to be limited by any theory, this feature of no dusting can be due to a possible trapping of the low Mw fraction in the polymer matrix. To further examine film applications for the linear PE films synthesized, the effect of mixing the linear PE films with other commercial PE films on its dusting characteristic was investigated. As reference, monolayer 1.5-mil blown films containing SCLAIR®FP120-A Resin, a commercial linear low-density PE (LLDPE) mixed with SURPASS HPs167‐AB Resin, a commercial high-density PE (HDPE) at different mixing ratios were prepared on the 2.5-inch Gloucester blown line using the process conditions as described herein above. Similarly, Sample 1P8 from Series II was mixed with the SURPASS HPs167‐AB Resin and converted into 1.5-mil monolayer films. As summarized in Table 5, in all cases, the linear PE film reduced the dusting compared to the blend with the commercial LLDPE. Table 5. Dusting Characteristic of Blend of PE Films Sample Area% Commercial LLDPE + 20% HDPE (ref.) 6 Commercial LLDPE + 60% HDPE (ref.) 30 Commercial LLDPE + 60% HDPE + talc (ref.) 34 Sample 1P8 with NA + 20% HDPE 0 Sample 1P8 with NA + 60% HDPE 11 Sample 1P8 with NA + 80% HDPE 22 Sample 1P8 with NA + 60% HDPE + talc 3 Sample 1P8 with NA (ref.) 2 Further, selected references and linear PE-HDPE blend samples were also characterized for their water vapor and oxygen barrier properties. As summarized in Table 6, replacing the commercial LLDPE in the blend with Sample 1P8 with the nucleating agent improved by about 36-38% in water vapor barrier and about 37-46% in oxygen barrier. Table 6. Dusting Characteristic of Blend of PE Films Sample Water Vapor Oxygen Transmission Transmission Rate Rate (OTR) (WVTR) (cm3-mil / 100 in2-day) (g-mil / 100 in2-day) Commercial LLDPE + 60% HDPE (ref.) 0.366 137.79 Commercial LLDPE + 60% HDPE + talc (ref.) 0.382 144.00 Sample 1P8 with NA + 60% HDPE 0.235 86.57 Sample 1P8 with NA + 60% HDPE + talc 0.236 77.30 The results demonstrate that the barrier property depended on the polymer design even using the same catalyst platform, polymerization process and comonomer type. In addition, further physical characterization by atomic force microscopy (AFM) (not shown) indicated a crystal morphology of arrangement of lamellae or “rows” mixed with spherulitic crystal. Although not wishing to be limited by any theory, the results suggested the crystallization with flow orientation to some degree. Two Catalysts The two-catalyst linear PE samples were produced in the pilot-scale, three-rector, in- series solution-phase polymerization process described hereinabove for the single catalyst linear PE samples with the main differences being that a Hf-based bridged metallocene catalyst formulation was injected into the first reactor and a Ti-based inline Ziegler-Natta catalyst formulation was injected into the second reactor. In the Examples of two-catalyst polymerization, no catalyst or fresh reactants were added to the third reactor. Octene was used as a comonomer. Four samples with different polymer architecture and melting temperature profile were obtained. 1-octene and hydrogen to the first and second reactors and in the removal of product. Methylpentane was used as the process solvent (a commercial blend of methylpentane isomers). Monomer (ethylene) and comonomer (1-octene) were purified prior to addition to the reaction using conventional feed preparation systems (such as contact with various absorption media to remove impurities such as water, oxygen and polar contaminants). In linear PE sample 2P1, the volume of the first CSTR reactor (R1) was 3.2 gallons (12 L), and the volume of the second CSTR reactor (R2) was 5.8 gallons (22 L). The volume of the tubular reactor (R3) was 4.755 gallons (18 L). In linear PE samples 2P2, 2P3 and 2P5, the volume of the first CSTR reactor (R1) was 3.2 gallons (12 L), and the volume of the second CSTR reactor (R2) was 5.8 gallons (22 L). The volume of the tubular reactor (R3) was 0.6 gallons (2.2 L). The Hf-based bridged metallocene catalyst formulation included the following components: component A, diphenylmethylene(cyclopentadienyl)(2,7-di-t- butylfuorenyl)hafnium dimethide [(2,7-tBu2Flu)Ph2C(Cp)HfMe2]; component M, methylaluminoxane (MMAO-07); component B, trityl tetrakis(pentafluoro-phenyl)borate (trityl borate); and component P, 2,6-di-tert-butyl-4-ethylphenol (BHEB). Methylaluminoxane (MMAO-07); and 2,6-di-tert-butyl-4-ethylphenol are premixed in-line and then combined with diphenylmethylene(cyclopentadienyl)(2,7-di-t- butylfuorenyl)hafnium dimethide and trityl tetrakis(pentafluoro-phenyl)borate just before entering the polymerization reactor (R1). The following catalyst component solvents were used: methylpentane for components M and P; and xylene for component A and B. The efficiency of the bridged metallocene catalyst formulation was optimized by adjusting the quantity of component A added to R1, the mole ratios of the catalyst components—i.e., [M] / [A], [P] / [M] and [B] / [A]—and the R1 catalyst inlet temperature. In samples 2P1–2P3 and 2P5, the quantity of component A added to R1 was 0.43, 0.8, 0.65 and 1.62 ppm, respectively. In samples 2P1–2P3 and 2P5, the mole ration of component M to component A was 60, 60, 60 and 40, respectively. In samples 2P1–2P3 and 2P5, the mole ration of component P to component M was 0.16, 0.16, 0.16 and 0.20, respectively. In samples 2P1– 2P3 and 2P5, the mole ration of component B to component A was 1.3, 1.3, 1.3 and 1.16, respectively. In samples 2P1–2P3 and 2P5, the catalyst inlet temperature was 27.6, 28.5, 17.8 and 18°C, receptively. The in-line Ziegler-Natta catalyst formulation catalyst had the following components: butyl ethyl magnesium [component v]; tertiary butyl chloride [component vi]; titanium tetrachloride [component vii]; diethyl aluminum ethoxide [component viii]; and triethyl aluminum [component ix]. Methylpentane was used as the catalyst component solvent and the in-line Ziegler-Natta catalyst formulation was prepared using the following steps and then injected into the second reactor (R2). In step one, a solution of triethylaluminum and butyl ethyl magnesium (Mg:Al = 20 mol:mol) was combined with a solution of tertiary butyl chloride and allowed to react for about 30 seconds to produce a MgCl2 support. In step two, a solution of titanium tetrachloride was added to the mixture formed in step one and allowed to react for about 14 seconds prior to injection into second reactor (R2). The in-line Ziegler- Natta catalyst was activated in the reactor by injecting a solution of diethyl aluminum ethoxide into R2. The efficiency of the in-line Ziegler-Natta catalyst formulation was optimized by adjusting the quantity of titanium tetrachloride added to the reactor, the mole ratios of the catalyst components—i.e., [vi] / [v], [viii] / [vii] and [ix] / [vii]—and R2 catalyst inlet temperature. In samples 2P1–2P3 and 2P5, the quantity of titanium tetrachloride added to R2 was 6.55, 8.13, 7.71 and 8.96, respectively. In samples 2P1–2P3 and 2P5, the mole ratio of [vi] / [v] in R2 was about 2. In samples 2P1–2P3 and 2P5, the mole ratio of [viii] / [vii] in R2 was 1.35. In samples 2P1–2P3 and 2P5, the mole ratio of [ix] / [vii] was 0.37. In samples 2P1– 2P3 and 2P5, the R2 catalyst inlet temperature was 35.0, 34.7, 25.6 and 27.2°C, respectively. The two-catalyst Examples were produced at a target density of 0.922 g / cm3where the total amount of ethylene supplied to the process was portioned or split between the two reactors R1 and R2. This operational variable (ethylene split or ES) is herein defined according to the weight percent of ethylene injected in R1 and R2, respectively; with the proviso that ESR1+ ESR2= 100% and ESR3= 0%. Comonomer (1-octene) was also added to the continuous solution polymerization process and was proportioned or split between R1 and R2. This operational variable (octene split or OS) is herein defined according to the weight percent of 1-octene comonomer that was injected in R1 and R2, respectively; with the proviso that OSR1+ OSR2= 100% and OSR3= 0%. In samples 2P1, 2P2, 2P4 and 2P5, the ethylene split to the reactors R1 and R2— ESR1 / ESR2—were all set at 45% / 55%. In samples 2P1, 2P2, 2P4 and 2P5, the 1-octene split to the reactors R1 and R2—OSR1 / OSR2—were 30% / 70%, 100% / 0%, 70% / 30% and 22% / 78%, respectively. In operating the continuous solution polymerization process in samples 2P1, 2P2, 2P4 and 2P5, ethylene, 1-octene and process solvent were combined to form a first fresh feed stream RF1 and then injected into the first reactor R1. Similarly, in operating the continuous solution polymerization process in samples 2P1, 2P2, 2P4 and 2P5, ethylene, 1-octene and process solvent were combined to form a second fresh feed stream RF2 and then injected into the second reactor R2. In samples 2P1, 2P2, 2P4 and 2P5, the temperature of the first fresh feed stream was 30°C. In samples 2P1, 2P2, 2P4 and 2P5, the temperature of the second fresh feed stream RF2 was 40.0°C, 39.9°C, 40.1°C and 40.1°C, respectively. In operating the continuous solution polymerization in samples 2P1, 2P2, 2P4 and 2P5, the second reactor R2 had a mean temperature (TR2) greater than the mean temperature of the first reactor R1 (TR1). To be clear, samples 2P1, 2P2, 2P4 and 2P5 were operated at a TR1 / TR2of 161.0°C / 205.1°C, 156.9°C / 204.3°C, 162.4°C / 205.1°C and 157.4°C / 1205.3°C. In operating the continuous solution polymerization process in samples 2P1, 2P2, 2P4 and 2P5, the third reactor R3 had an exit temperature (TR3exit) equal or less than the mean temperature of the second reactor R2 (TR2)—e.g., –15°C ≲ TR3exit – TR2≤ 0°C. In operating the continuous solution polymerization process shown in samples 2P1, 2P2, 2P4 and 2P5, the total amount of ethylene polymerized in each reactor is monitored. The term QR1refers to the percent of the ethylene added to R1 that was polymerized by the catalyst formulation. Similarly, QR2and QR3represent the percent of the ethylene added to R2 and residual ethylene flown into R3 from R1 and R2 that were polymerized. Samples 2P1, 2P2, 2P4 and 2P5 had a QR1 / QR2 / QR3of 77.9% / 96.4% / 74.3%, 81.0% / 91.3% / 27.7%, 77.9% / 93.3% / 39.2% and respectively. The total or overall ethylene conversion (QT) across the entire continuous solution polymerization process—i.e., QT= 100 × [weight of ethylene in the ethylene polymer composition] / ([weight of ethylene in the ethylene polymer composition] + [weight of unreacted ethylene]—was also monitored. Samples 2P1, 2P2, 2P4 and 2P5 had a QTof 97.7, 94.5%, 95.7% and 97.3%, respectively. In operating the continuous solution polymerization process for preparing samples 2P1, 2P2, 2P4 and 2P5, hydrogen was injected into the first reactor R1 and the second reactor R2 to control (reduce) the molecular weight of the polymerized species. To be specific, in samples 2P1, 2P2, 2P4 and 2P5, the weight percent of hydrogen in the inlet stream of R1 and R2 (H2R1 / H2R2) were 3.74 / 44.00, 0.70 / 43.95, 1.00 / 39.98 and 1.30 / 39.98, respectively. CSTR reactors R1 and R2 were continuously stirred by a stirring assembly which included a motor external teach reactor and an agitator within each reactor. In samples 2P1, 2P2, 2P4 and 2P5, the rate of agitation for R1 and R2 were 500 rpm and 260 rpm, respectively. In samples 2P1, 2P2, 2P4 and 2P5, the rate of agitation for R1 / R2 were 690 rpm / 260 rpm, 325 rpm / 260 rpm, 325 rpm / 260 rpm and 325 rpm / 260 rpm, respectively. Polymerization in the continuous solution polymerization process was terminated by adding a catalyst deactivator to the stream exiting the tubular reactor (R3). The catalyst deactivator used was octanoic acid (caprylic acid), commercially available from P&G Chemicals, Cincinnati, OH, U.S.A. The catalyst deactivator was added such that the moles of fatty acid added were 50% of the total molar amount of catalytic metal and aluminum added to the polymerization process; to be clear, the moles of octanoic acid added = 0.5 × (moles titanium + moles aluminum). A two-stage devolatilization process was employed to recover the linear PE samples 2P1, 2P2, 2P4 and 2P5 from the process solvent, i.e., two vapor / liquid separators were used, and the second bottom stream (from the second V / L separator) was passed through a gear pump / pelletizer combination. The gear pump was a VACOREX 45 / 45 pump with 191 liter per hour capacity which was steam jacketed with 270# steam. The ethylene polymer composition leaving the gear pump was then passed through a 4” diameter static mixer before entering the pelletizer where the ethylene polymer composition was forced through the holes in the die plate top down. There were 32 holes on the die with a hole diameter of 0.125”. the aspect ratio (i.e., length-to-diameter ratio) for each hole was 6.3:1 and the die had a thickness of 1.63” and a diameter of 12”. There were 6 cutter knives—8.6878” OD sweep and 6.2418 ID sweep—located on the side of the die that faced the cooling water system. There were internal heating channels within the die plate and die body and plate were heated with 600# or 270# steam. Cooling water system had a temperature range of from 10 to 80°C and a flow of 7500–9500 kg / h. DHT-4V (hydrotalcite), supplied by Kyowa Chemical Industry Co. LTD, Tokyo, Japan was used as a passivator, or acid scavenger, in the continuous solution process. A slurry of DHT-4V in process solvent was added prior to the first V / L separator. Prior to pelletization, the linear PE samples 2P1, 2P2, 2P4 and 2P5 were stabilized by adding 500 ppm of IRGANOX 1076 (a primary antioxidant) and 500 ppm of IRGAFOS 168 (a secondary antioxidant), based on weight of the linear PE sample. Antioxidants were dissolved in process solvent and added between the first and second V / L separators. Film products with nucleating agent were obtained by adding a masterbatch of HYPERFORM HPN 20E to the extruder during the film production step. The target amount of nucleating agent in the linear PE was 1,200 ppm. For film property characterization (e.g., barrier properties), a blown monolayer film (1.5 mil) was prepared and used for each measurement. Blown films were generated by using a 2.5-inch Gloucester blown film line (L / D = 24) with a die diameter of 4-inch. A set of fixed process conditions of a die gap of 35 mils (0.0889 cm), a blow-up ratio (BUR) of 2.5, a frost line height of about 24 inches, and an output rate of 100 lbs / hr was used for all films prepared from the linear PE samples 2P1, 2P2, 2P4 and 2P5. All samples with the nucleating agent contained 3 weight percent of a master batch of 4 weight percent HYPERFORM HPN 20E in an ethylene homopolymer carrier resin to reach a target nucleating agent content of 1,200 ppm. To avoid melt fracture, all samples contained 2 weight percent of a process aid masterbatch which was a 5 weight percent masterbatch of 3M DYNAMAR FX 5920A in an LLDPE carrier resin to reach a target process aid content of 1,000 ppm. The two-catalyst linear PE samples were dry blended with the process aid masterbatch, or process aid masterbatch and the nucleating agent masterbatch prior to the extrusion step using a WSB-241-T MAGUIRE blender. The effect of the addition of nucleating agent on the resulting barrier properties was examined by comparing the samples with and without the nucleating agent. Table 7. Linear PE Polymer Material Properties Product 2P1 2P2 2P4 2P5 Catalyst Hf-based Metallocene Catalyst (First Reactor) and Ziegler-Natta Catalyst (Second Reactor) Density (g / cm3) 0.924 0.922 0.922 0.923 Melt Index (I2) (g / 10 min) 1.90 1.93 1.70 1.27 Melt Flow Ratio (I21 / I2) 58.96 53.68 62.36 53.54 Comonomer cont. (mol%) 2.7 3.3 3.1 2.8 Weight ave. mol. weight 82,033 87,728 90,418 86,762 (Mw) (g / mol) Number ave. mol. weight 16,953 22,962 18,938 19,643 (Mn) (g / mol) Mw / Mn 4.84 3.82 4.77 4.42 Hexene Extractables (%) 0.83 0.32 0.40 0.65 Table 8. Barrier and Optical Properties of Linear PE Film with Nucleating Agent (NA) Product 2P1 2P2 2P4 2P5 Water Vapor Transmission 1.049 1.046 1.100 1.131 Rate (WVTR) – no NA (g-mil / 100 in2-day) WVTR – with NA 0.855 0.809 0.841 0.852 (g / 100 in2-day) Oxygen Transmission 399.0 439.2 412.5 445.5 (OTR) – no NA (cm3-mil / 100 in2-day) OTR – with NA 318.9 309.0 320.4 369.9 (cm3-mil / 100 in2-day) 45º Gloss – with NA 47.3 43.9 47.7 51.8 Total Haze – with NA (%) 14.1 16.8 14.4 12.5 Energy at Break in Puncture 54.0 54.1 64.4 62.9 Test – with NA (J / mm) Figure 13 shows gel permeation chromatographs (GPC) with FTIR for linear PE in accordance with other embodiments (2P1-2P5). The Mw, Mn, and Mw / Mn are generally within the range that is applicable for various PE applications. In Figure 13, all samples exhibited broad distributions having a shoulder to higher Mw without a clear distinction. As summarized in Table 7, the density was in the range from 0.922 to 0.924 g / cm3across the samples, within the within the range of low-density polyethylene (LDPE). Further, the melt index (I2) was maintained at a relatively low level (e.g., < 2 g / 10 min) for all the samples. The melt flow ratio ranged from 53.7 to 62.4. The Mw, Mn, and Mw / Mn were generally within the range that is applicable for various PE applications. The comonomer content was from 2.7 to 3.3 mol% having a reverse or highly reverse comonomer distribution (Figure 13). In addition, the samples exhibited less than 1% of hexene extractables. As summarized in Table 8, both water vapor barrier property and oxygen barrier property were improved by the addition of the nucleating agent. The water vapor transmission rate (WVTR) was reduced by about 19-25%, and the oxygen transmission rate (OTR) by about 17-30%. These barrier properties were comparable with or better than some reference samples with higher densities in the range of medium-density PE (MDPE) and high-density PE (HDPE). Grease barrier property of sample 2P1 was evaluated. The area percentile of grease permeance was 18% without the nucleating agent and 23% with the nucleating agent, which was comparable to a commercial LLDPE sample (19%). All samples (2P1-2P5) showed better puncture resistance than the reference (33.8 J / mm) (Table 8 and Figure 10). Further, the samples showed about twice better tear resistance than the reference in both directions (MD and TD) (Table 8 and Figure 11). As shown in Figure 9, 1% secant modulus was about 20-45% lower than the reference PE standard films while exhibiting better water or oxygen barrier properties. Embodiments An embodiment described herein provides a linear polyethylene (PE) polymer product having a density of from 0.922 to 0.940 g / cm3and a water vapor transmission rate (WVTR) of 1.0 g-mil / 100 in2-day or less, where the PE polymer product includes from 100 to 3,000 ppm of a nucleating agent. In an embodiment, combinable with any other embodiment, the nucleating agent includes a coordination polymer. In an embodiment, combinable with any other embodiment, the nucleating agent includes a metal salt. In an embodiment, combinable with any other embodiment, the nucleating agent includes a calcium salt. In an embodiment, combinable with any other embodiment, the nucleating agent includes a salt of a carboxylic acid. In an embodiment, combinable with any other embodiment, the nucleating agent includes a calcium salt of 1,2 cyclohexanedicarboxylic acid. In an embodiment, combinable with any other embodiment, the density is from 0.922 to 0.925 g / cm3. In an embodiment, combinable with any other embodiment, the PE polymer product has an oxygen transmission rate (OTR) of 450 cm3-mil / 100 in2-day or less. In an embodiment, combinable with any other embodiment, the PE polymer product has a melt index (MI) of from 0.5 to 2.0 g / 10 min. In an embodiment, combinable with any other embodiment, the PE polymer product has a weight average molecular weight (Mw) of from 80,000 to 130,000. In an embodiment, combinable with any other embodiment, the PE polymer product has a number average molecular weight (Mn) less than 30,000. In an embodiment, combinable with any other embodiment, the PE polymer product has a molecular weight distribution (Mw / Mn) of from 4 to 6. In an embodiment, combinable with any other embodiment, the PE polymer product has 1% secant modulus in machine direction (MD) of from 200 to 400 MPa. In an embodiment, combinable with any other embodiment, the PE polymer product has a puncture resistance of from 40 to 70 J / mm. In an embodiment, combinable with any other embodiment, the PE polymer product has a tear resistance of from 50 to 300 g / mil in machine direction. In an embodiment, combinable with any other embodiment, the PE polymer product has a tear resistance of from 300 to 600 g / mil in transverse direction. In an embodiment, combinable with any other embodiment, the PE polymer product is synthesized by a multi reactor solution polymerization process using a metallocene catalyst. In an embodiment, combinable with any other embodiment, the PE is synthesized by a multi reactor solution polymerization process; and the PE has a bimodal molecular weight distribution from a first and a second polymer fractions, where: the first polymer fraction has a weight average molecular weight of from 17,000 to 65,000 and a number average molecular weight of from 8,000 to 32,000; and the second polymer fraction has a molecular weight of from 184,000 to 220,000. In an embodiment, the first polymer fraction accounts for 55 wt% of the PE polymer product or greater. Another embodiment described herein provides a method of synthesizing a linear polyethylene (PE) polymer product, where the method includes: forming a first polymer solution by polymerizing ethylene in a solvent in a first stirred polymerization reactor at a temperature of from 80 to 200°C and a pressure of from 1,500 to 5,000 psi in the presence of a first catalyst; passing the first polymer solution into a second stirred polymerization reactor; forming a second polymer solution from the first polymer solution by polymerizing ethylene in the second stirred polymerization reactor in the presence of a second catalyst; phase separating the second polymer solution to recover a linear polyethylene polymer, the linear polyethylene polymer having a density of from 0.922 to 0.940 g / cm3; passing the linear polyethylene polymer into an extruder to form the linear PE polymer product, where the linear PE polymer product has a water vapor transmission rate (WVTR) of 1.0 g-mil / 100 in2-day or less. In an embodiment, combinable with any other embodiment, the first catalyst or the second catalyst includes an organometallic complex of a group 3, 4 or 5 metal, the organometallic complex including a phosphinimine ligand. In an embodiment, combinable with any other embodiment, the first and second catalysts are the same catalyst. In an embodiment, combinable with any other embodiment, the method further includes adding a cocatalyst including an ionic activator to the first stirred polymerization reactor. In an embodiment, combinable with any other embodiment, the method further includes adding a nucleating agent to the extruder. In an embodiment, combinable with any other embodiment, the PE polymer product has an oxygen transmission rate (OTR) of 450 cm3-mil / 100 in2-day of less. Another embodiment described herein provides a method of synthesizing a linear polyethylene (PE) polymer product, where the method includes: forming a first polymer solution by polymerizing ethylene in a solvent in a first stirred polymerization reactor in the presence of a first catalyst and a comonomer; passing the first polymer solution into a second stirred polymerization reactor; and forming a second polymer solution form the first polymer solution by polymerizing ethylene in the second stirred polymerization reactor in the presence of a second catalyst and the comonomer; phase separating the second polymer solution to recover a linear polyethylene polymer, the linear polyethylene polymer having a density of from 0.922 to 0.940 g / cm3and a comonomer concentration of from 2 to 4 mol%; passing the linear polyethylene polymer into an extruder; and adding a nucleating agent including a calcium salt of 1,2 cyclohexanedicarboxylic acid to the extruder to form the linear PE polymer product, where the PE polymer product includes the nucleating agent. In an embodiment, combinable with any other embodiment, the PE polymer product has an oxygen transmission rate (OTR) of 500 cm3-mil / 100 in2-day or less. In an embodiment, combinable with any other embodiment, the PE polymer product has a water vapor transmission rate (WVTR) of 1.0 g-mil / 100 in2-day or less. In an embodiment, combinable with any other embodiment, the forming of the PE polymer product is dusting-free. In an embodiment, combinable with any other embodiment, the method further includes blending the PE polymer product with another polymer product. In an embodiment, combinable with any other embodiment, the method further includes forming a packaging including more than one film, the packing including a layer of the PE polymer product. In an embodiment, combinable with any other embodiment, the comonomer includes a C3-10 alpha-olefin. In an embodiment, combinable with any other embodiment, the comonomer includes 1-octene. Another embodiment described herein provides a linear polyethylene (PE) polymer product having a density of from 0.922 to 0.925 g / cm3, a water vapor transmission rate (WVTR) of 1.0 g-mil / 100 in2-day or less, an oxygen transmission rate (OTR) of 450 cm3- mil / 100 in2-day or less, and has 1% secant modulus in machine direction (MD) of from 200 to 400 MPa, where the PE polymer product includes from 100 to 3,000 ppm of a nucleating agent. In an embodiment, combinable with any other embodiment, the PE polymer product has a puncture resistance of from 40 to 70 J / mm. In an embodiment, combinable with any other embodiment, the PE polymer product has a tear resistance of from 50 to 300 g / mil in machine direction. In an embodiment, combinable with any other embodiment, the PE polymer product has a tear resistance of from 300 to 600 g / mil in transverse direction. Another embodiment described herein provides a polyethylene (PE) polymer blend product including a linear low-density PE (LLDPE) and a high-density PE (HDPE), where the PE blend product has a water vapor transmission rate (WVTR) of 0.3 g-mil / 100 in2-day or less, an oxygen transmission rate (OTR) of 100 cm3-mil / 100 in2-day or less, where the LLDPE has 1% secant modulus in machine direction (MD) of from 200 to 400 MPa, and where the LLDPE includes from 100 to 3,000 ppm of a nucleating agent. INDUSTRIAL APPLICABILITY Linear polyethylene polymer product of the present disclosure contains from 100 to 3,000 ppm of a nucleating agent and has a density of from 0.922 to 0.940 g / cm3and a water vapor transmission rate (WVTR) of 1.0 g-mil / 100 in2-day or less. The linear polyethylene polymer product may be used in various packaging applications where a good balance of mechanical, optical and barrier properties is required.

Claims

CLAIMS 1. A linear polyethylene (PE) polymer product having a density of from 0.922 to 0.940 g / cm3and a water vapor transmission rate (WVTR) of 1.0 g-mil / 100 in2-day or less, wherein the PE polymer product comprises from 100 to 3,000 ppm of a nucleating agent.

2. The PE polymer product of claim 1, wherein the nucleating agent comprises a coordination polymer.

3. The PE polymer product of claim 1 or 2, wherein the nucleating agent comprises a metal salt.

4. The PE polymer product of claims 1-3, wherein the nucleating agent comprises a calcium salt.

5. The PE polymer product of claims 1-4, wherein the nucleating agent comprises a salt of a carboxylic acid.

6. The PE polymer product of one of claims 1-3, wherein the nucleating agent comprises a calcium salt of 1,2 cyclohexanedicarboxylic acid.

7. The PE polymer product of one of claims 1-6, wherein the density is from 0.922 to 0.925 g / cm3.

8. The PE polymer product of one of claims 1-7, wherein the PE polymer product has an oxygen transmission rate (OTR) of 450 cm3-mil / 100 in2-day or less.

9. The PE polymer product of one of claims 1-8, wherein the PE polymer product has a melt index (MI) of from 0.5 to 2.0 g / 10 min.

10. The PE polymer product of one of claims 1-9, wherein the PE polymer product has a weight average molecular weight (Mw) of from 80,000 to 130,000.

11. The PE polymer product of one of claims 1-10, wherein the PE polymer product has a number average molecular weight (Mn) less than 30,000.

12. The PE polymer product of one of claims 1-11, wherein the PE polymer product has a molecular weight distribution (Mw / Mn) of from 4 to 6.

13. The PE polymer product of one of claims 1-12, wherein the PE polymer product has 1% secant modulus in machine direction (MD) of from 200 to 400 MPa.

14. The PE polymer product of one of claims 1-13, wherein the PE polymer product has a puncture resistance of from 40 to 70 J / mm.

15. The PE polymer product of one of claims 1-14, wherein the PE polymer product has a tear resistance of from 50 to 300 g / mil in machine direction.

16. The PE polymer product of one of claims 1-15, wherein the PE polymer product has a tear resistance of from 300 to 600 g / mil in transverse direction.

17. The PE polymer product of one of claims 1-16, wherein the PE polymer product is synthesized by a multi reactor solution polymerization process using a metallocene catalyst.

18. The PE polymer product of one of claims 1-17, wherein: the PE is synthesized by a multi reactor solution polymerization process; and the PE has a bimodal molecular weight distribution from a first and a second polymer fractions, wherein: the first polymer fraction has a weight average molecular weight of from 17,000 to 65,000 and a number average molecular weight of from 8,000 to 32,000; and the second polymer fraction has a molecular weight of from 184,000 to 220,000.

19. The PE polymer product of claim 18, wherein the first polymer fraction accounts for 55 wt% of the PE polymer product or greater.

20. A method of synthesizing a linear polyethylene (PE) polymer product, the method comprising: forming a first polymer solution by polymerizing ethylene in a solvent in a first stirred polymerization reactor at a temperature of from 80 to 200°C and a pressure of from 1500 to 5000 psi in the presence of a first catalyst; passing the first polymer solution into a second stirred polymerization reactor; forming a second polymer solution from the first polymer solution by polymerizing ethylene in the second stirred polymerization reactor in the presence of a second catalyst; phase separating the second polymer solution to recover a linear polyethylene polymer, the linear polyethylene polymer having a density of from 0.922 to 0.940 g / cm3; passing the linear polyethylene polymer into an extruder to form the linear PE polymer product, wherein the linear PE polymer product has a water vapor transmission rate (WVTR) of 1.0 g-mil / 100 in2-day or less.

21. The method of claim 20, wherein the first catalyst or the second catalyst comprises an organometallic complex of a group 3, 4 or 5 metal, the organometallic complex comprising a phosphinimine ligand.

22. The method of claim 20 or 21, wherein the first and second catalysts are the same catalyst.

23. The method of one of claims 20-22 further comprising adding a cocatalyst comprising an ionic activator to the first stirred polymerization reactor.

24. The method of one of claims 20-23, further comprising adding a nucleating agent to the extruder.

25. The method of one of claims 20-21, wherein the PE polymer product has an oxygen transmission rate (OTR) of 450 cm3-mil / 100 in2-day of less.

26. A method of synthesizing a linear polyethylene (PE) polymer product, the method comprising: forming a first polymer solution by polymerizing ethylene in a solvent in a first stirred polymerization reactor in the presence of a first catalyst and a comonomer; passing the first polymer solution into a second stirred polymerization reactor; and forming a second polymer solution form the first polymer solution by polymerizing ethylene in the second stirred polymerization reactor in the presence of a second catalyst and the comonomer; phase separating the second polymer solution to recover a linear polyethylene polymer, the linear polyethylene polymer having a density of from 0.922 to 0.940 g / cm3and a comonomer concentration of from 2 to 4 mol%; passing the linear polyethylene polymer into an extruder; and adding a nucleating agent comprising a calcium salt of 1,2 cyclohexanedicarboxylic acid to the extruder to form the linear PE polymer product, wherein the PE polymer product comprises the nucleating agent.

27. The method of claim 26, wherein the PE polymer product has an oxygen transmission rate (OTR) of 500 cm3-mil / 100 in2-day or less.

28. The method of claim 26 or 27, wherein the PE polymer product has a water vapor transmission rate (WVTR) of 1.0 g-mil / 100 in2-day or less.

29. The method of one of claims 26-28, wherein the forming of the PE polymer product is dusting-free.

30. The method of one of claims 26-29, further comprising blending the PE polymer product with another polymer product.

31. The method of one of claims 26-30, further comprising forming a packaging comprising more than one film, the packing comprising a layer of the PE polymer product.

32. The method of one of claims 26-31, wherein the comonomer comprises a C3-10 alpha-olefin.

33. The method of one of claims 26-32, wherein the comonomer comprises 1-octene.

34. A linear polyethylene (PE) polymer product having a density of from 0.922 to 0.925 g / cm3, a water vapor transmission rate (WVTR) of 1.0 g-mil / 100 in2-day or less, an oxygen transmission rate (OTR) of 450 cm3-mil / 100 in2-day or less, and has 1% secant modulus inmachine direction (MD) of from 200 to 400 MPa, wherein the PE polymer product comprises from 100 to 3,000 ppm of a nucleating agent.

35. The PE polymer product of claim 34, wherein the PE polymer product has a puncture resistance of from 40 to 70 J / mm.

36. The PE polymer product of claim 34 or 35, wherein the PE polymer product has a tear resistance of from 50 to 300 g / mil in machine direction.

37. The PE polymer product of one of claims 34-36, wherein the PE polymer product has a tear resistance of from 300 to 600 g / mil in transverse direction.

38. A polyethylene (PE) polymer blend product comprising a linear low-density PE (LLDPE) and a high-density PE (HDPE), wherein the PE blend product has a water vapor transmission rate (WVTR) of 0.3 g-mil / 100 in2-day or less, an oxygen transmission rate (OTR) of 100 cm3-mil / 100 in2-day or less, wherein the LLDPE has 1% secant modulus in machine direction (MD) of from 200 to 400 MPa, and wherein the LLDPE comprises from 100 to 3,000 ppm of a nucleating agent.

Images